# Algernon: Auto-refresh SSE event server binds to all interfaces with Access-Control-Allow-Origin: \* and no authentication

Advisory record · `GHSA-9v4j-7g44-qcqw`

- **Identifiers:** `GHSA-9v4j-7g44-qcqw` · `GO-2026-5300`
- **State:** Confirmed
- **Severity:** CVSS 5.3 Medium
- **Critical:** No
- **Weakness (CWE):** [CWE-200](https://cwe.mitre.org/data/definitions/200.html) · [CWE-306](https://cwe.mitre.org/data/definitions/306.html) · [CWE-942](https://cwe.mitre.org/data/definitions/942.html) · [CWE-1188](https://cwe.mitre.org/data/definitions/1188.html)
- **Tags:** [Information disclosure](https://agentprime.io/advisories/tag/info-disclosure.md) · [Authentication bypass](https://agentprime.io/advisories/tag/auth-bypass.md) · [CWE-942](https://agentprime.io/advisories/tag/cwe-942.md) · [CWE-1188](https://agentprime.io/advisories/tag/cwe-1188.md)
- **Published:** 19 May 2026
- **Updated:** 25 Jun 2026
- **Reviewed by a person:** No

Published by the GitHub Advisory Database at 19 May 2026, 14:36 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Affected packages

- `github.com/xyproto/algernon` (Go): affected `<1.17.7`; fixed in `1.17.7`

## Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

## Severity and exploitation

- 5.3 Medium, CVSS 3.1: `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N`, from GitHub Advisory Database

- **CISA KEV:** Not listed.
- **EPSS:** No score.

## Timeline

- 31 Oct 2026, 15:07 UTC: First seen by agentprime
- 31 Oct 2026, 15:07 UTC: [Confirmed by OSV](https://osv.dev/vulnerability/GHSA-9v4j-7g44-qcqw)

## Sources

- [GitHub Advisory Database: GHSA-9v4j-7g44-qcqw](https://github.com/advisories/GHSA-9v4j-7g44-qcqw)
- [OSV: GHSA-9v4j-7g44-qcqw](https://osv.dev/vulnerability/GHSA-9v4j-7g44-qcqw)
- <https://github.com/xyproto/algernon/security/advisories/GHSA-9v4j-7g44-qcqw>
- <https://github.com/xyproto/algernon>

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.

## Check whether this affects you

A Match means an installed version is in the affected range above. Most don’t affect the app; agentprime hasn’t analysed this one yet.

- With the agentprime MCP server (<https://api.agentprime.io/mcp>), ask your agent to check the project: `check_lockfile` sends a lockfile, `check_packages` a list of installed packages, and both return the Matches and the upgrades that clear them. `get_advisory` returns this record. Setup: <https://agentprime.io/mcp.md>
- In a browser: <https://agentprime.io/check/> reads your lockfile in the browser, never uploading it.
- Whether it touches your code, with file and line: the Claude Code plugin, <https://agentprime.io/plugin.md>
- As JSON: <https://api.agentprime.io/v1/advisories/GHSA-9v4j-7g44-qcqw>, or `POST https://api.agentprime.io/v1/match` with your packages (<https://agentprime.io/api.md>)

---

The web page: <https://agentprime.io/advisories/GHSA-9v4j-7g44-qcqw/>. Everything for agents: <https://agentprime.io/llms.txt>.